Semiconductor light- emitting element, semiconductor light- emitting device, method for producing semiconductor light- emitting element, method for producing semiconductor light- emitting device, illumination device using semiconductor light-emitting device, and electronic apparatus

ABSTRACT

The disclosed semiconductor light-emitting element is configured from layering an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer ( 160 ); and a first electrode ( 200 ), which is the cathode, is formed on the p-type semiconductor layer ( 160 ). Also, between the p-type semiconductor layer ( 160 ) and a reflecting layer ( 220   b ), the first electrode ( 200 ) is provided with a crystalline first transparent electrode layer ( 210 ) and a non-crystalline second transparent electrode layer ( 220   a ). The crystalline first transparent electrode layer ( 210 ) increases adhesion with the p-type semiconductor layer ( 160 ), and the non-crystalline second transparent electrode layer ( 220   a ) suppresses delamination of the reflecting layer ( 220   b ). Also, the first transparent electrode layer ( 210 ) and the second transparent electrode layer ( 220   a ) transmit light emitted from the light-emitting layer and suppress degradation of reflective characteristics. In this way, delamination of the reflecting layer and degradation of reflective characteristics are suppressed in a semiconductor light-emitting element mounted using flip-chip (FC) mounting.

TECHNICAL FIELD

The present invention relates to a semiconductor light-emitting element,a semiconductor light-emitting device, a method for producing thesemiconductor light-emitting element, a method for producing thesemiconductor light-emitting device, an illumination device using thesemiconductor light-emitting device, and an electronic apparatus.

BACKGROUND ART

Recently, a GaN-based compound semiconductor has become a focus ofattention as a semiconductor material of the light-emitting element ofshort wavelength light. The GaN-based compound semiconductor is formedby a metal organic chemical vapor deposition method (MOCVD method), amolecular beam epitaxy method (MBE method) or the like on a sapphiresingle crystal or other various oxides or group III-V compounds providedas a substrate.

In a semiconductor light-emitting element using the GaN-based compoundsemiconductor, a laminated semiconductor layer having a light-emittingdiode (LED) structure constituted by an n-type semiconductor layer, alight-emitting layer and a p-type semiconductor layer was formed on asubstrate and an electrode having optical transparency (transparentelectrode) was formed on the p-type semiconductor layer on the topportion, thereby extracting emitted light via the transparent electrode.

On some portions of the transparent electrode, which connect to bondingwires made of Au (gold), bonding pads made of Au or an alloy containingAu were formed. Since these bonding pads cut off light from thelight-emitting layer, it was impossible to extract emitted light fromthe light-emitting layer through the portions on the transparentelectrode where the bonding pads were formed.

Further, in the semiconductor light-emitting element, light travelingtoward the transparent electrode and light traveling toward thesubstrate are emitted from the light-emitting layer. Of these, the lighttraveling toward the substrate was absorbed by a package on which thesubstrate and the semiconductor light-emitting element were mounted orby an adhesive that bonds the semiconductor light-emitting element tothe package, and therefore, the light traveling toward the substrate wasdifficult to be extracted to the outside.

In contrast, by an FC (flip-chip bonding) mount technology, in which asemiconductor light-emitting element formed on a substrate that istransparent to light emission wavelength is reversed and mounted on acircuit board (submount) or a package, light is extracted from asubstrate side where no electrodes are formed to avoid light exclusionby electrodes, and thereby light extraction efficiency is improved.

Moreover, since, in the semiconductor light-emitting element and thecircuit board (submount), the electrodes of the semiconductorlight-emitting element and pads of wiring on the circuit board(submount) are connected with each other via bumps made of Au or thelike, an area on the circuit board (submount) required for mounting ofthe semiconductor light-emitting element is reduced and mounting can beperformed in high density, with high reliability in connection comparedto the method of connection with bonding wires.

By the way, for using the FC mount technology, the semiconductorlight-emitting element is configured such that both of the positiveelectrode and the negative electrode are taken out from a front surfaceside of the laminated semiconductor layer, which is opposite to thesubstrate, and a reflecting layer made of Ag (silver) or the like, whichhas high reflectance to the light emission wavelength, is provided onthe front surface side of the laminated semiconductor layer.Consequently, the light traveling toward the electrodes is reflected andextracted from the substrate side, and accordingly, the light extractionefficiency is further improved.

In the Patent Document 1, a semiconductor light-emitting element isdisclosed, in which a first conduction type semiconductor layer, alight-emitting layer, and a second conduction type semiconductor layerare laminated in this order, and an electrode connected to the secondconduction type semiconductor layer includes a lower layer conductiveoxide film, an upper layer conductive oxide film which is formed on thelower layer conductive oxide film so that a part of a front surface ofthe lower layer conductive oxide film may be exposed, and a metal filmdisposed only on the upper layer conductive oxide film. The lower layerconductive oxide film functions as a non-reflective film at the regionwhere the metal film is not disposed, and the upper layer conductiveoxide film functions as a reflective film having high reflectance to thelight emission wavelength at the region where the metal film isdisposed.

CITATION LIST Patent Literature

-   Patent Document 1: Japanese Patent Application Laid-open Publication    No. 2005-317931

SUMMARY OF INVENTION Technical Problem

In the FC-mounted semiconductor light-emitting element, the reflectinglayer is formed on the laminated semiconductor layer made of galliumnitride (GaN) or the like.

However, there are not necessarily excellent adhesiveness (bondingcharacteristics) between the laminated semiconductor layer and thereflecting layer. In the case where the adhesiveness are not good andthe reflecting layer is apt to be delaminated, a bonding layer isinterposed to improve the adhesiveness between the laminatedsemiconductor layer and the reflecting layer.

Since the reflecting layer also works as the electrode, the bondinglayer is required to have conductivity, and to make an ohmic contactwith each of the laminated semiconductor layer and the reflecting layer.Further, since the bonding layer exists between the reflecting layer andthe laminated semiconductor layer, the bonding layer degrades reflectivecharacteristics in the case where optical transparency to the lightemission wavelength from the light-emitting layer is poor.

It is an object of the present invention to suppress delamination of thereflecting layer of the semiconductor light-emitting element mounted byflip-chip (FC) bonding and degradation of reflective characteristics.

Solution to Problem

In order to attain the object, a semiconductor light-emitting element towhich the present invention is applied includes: a laminatedsemiconductor layer in which a first semiconductor layer having a firstconduction type, a light-emitting layer, and a second semiconductorlayer having a second conduction type that is opposite to the firstconduction type are laminated in order; a first transparent electrodelayer that is provided on the laminated semiconductor layer, hastransparency to light emitted from the light-emitting layer and iscrystalline; a second transparent electrode layer that is provided onthe first transparent electrode layer, has transparency to the light andis non-crystalline; and a reflecting layer that is provided on thesecond transparent electrode layer and is reflective to the light.

Such a semiconductor light-emitting element can be characterized in thatthe first transparent electrode layer which is crystalline and thesecond transparent electrode layer which is non-crystalline areconductive oxides.

Further, the semiconductor light-emitting element can be characterizedin that the first transparent electrode layer which is crystalline andthe second transparent electrode layer which is non-crystalline areconductive oxides containing any one of indium (In) and titanium (Ti).

Then, a thickness of the first transparent electrode layer which iscrystalline can be characterized to be in a range of 5 nm or more to 500nm or less. On the other hand, a thickness of the second transparentelectrode layer which is non-crystalline can be characterized to be in arange of 1 nm or more to 5 nm or less. Further, the reflecting layer canbe characterized to be any one of Ag and a metal containing Ag.

Moreover, the laminated semiconductor layer can be characterized in thatthe first conduction type of the first semiconductor layer is an n-typein which a carrier is an electron and the second conduction type of thesecond semiconductor layer is a p-type in which a carrier is a hole.

Still further, a semiconductor light-emitting device to which thepresent invention is applied includes: a semiconductor light-emittingelement including: a laminated semiconductor layer in which a firstsemiconductor layer having a first conduction type, a light-emittinglayer and a second semiconductor layer having a second conduction typethat is opposite to the first conduction type are laminated in order; afirst transparent electrode layer that is provided on the laminatedsemiconductor layer, has transparency to light emitted from thelight-emitting layer and is crystalline; a second transparent electrodelayer that is provided on the first transparent electrode layer, hastransparency to the light and is non-crystalline; and a reflecting layerthat is provided on the second transparent electrode layer and isreflective to the light; and a circuit board that is arranged to face aside including the reflecting layer of the semiconductor light-emittingelement.

Such a semiconductor light-emitting device can be characterized in that,in the semiconductor light-emitting element and the circuit board, apair of positive and negative connecting electrodes provided on the sideincluding the reflecting layer of the semiconductor light-emittingelement is connected to a pair of wirings provided on the circuit boardby a connector provided on the circuit board.

By the way, from another point of view, a method for producing asemiconductor light-emitting element to which the present invention isapplied includes: a process that forms a laminated semiconductor layerincluding a first semiconductor layer having a first conduction type, alight-emitting layer and a second semiconductor layer having a secondconduction type that is opposite to the first conduction type; a processthat forms a first transparent electrode layer on the laminatedsemiconductor layer, the first transparent electrode layer havingtransparency to light emitted from the light-emitting layer, and beingcrystalline; a process that forms a second transparent electrode layeron the first transparent electrode layer, the second transparentelectrode layer having transparency to the light, and beingnon-crystalline; and a process that forms a reflecting layer on thesecond transparent electrode layer, the reflecting layer reflecting thelight.

The process that forms a first transparent electrode layer can becharacterized by including a process that deposits a film to be thefirst transparent electrode layer and a process that applies heattreatment for crystallizing the film.

Further, a method for producing a semiconductor light-emitting device towhich the present invention is applied includes: a process that performsalignment to bring a pair of positive and negative connecting electrodesprovided on a side including a reflecting layer of a semiconductorlight-emitting element into correspondence with a pair of wiringsprovided on a circuit board, the semiconductor light-emitting elementincluding: a laminated semiconductor layer in which a firstsemiconductor layer having a first conduction type, a light-emittinglayer and a second semiconductor layer having a second conduction typethat is opposite to the first conduction type are laminated in order; afirst transparent electrode layer that is provided on the laminatedsemiconductor layer, has transparency to light emitted from thelight-emitting layer and is crystalline; a second transparent electrodelayer that is provided on the first transparent electrode layer, hastransparency to the light and is non-crystalline; and the reflectinglayer that is provided on the second transparent electrode layer and isreflective to the light; and a process that heats and presses thesemiconductor light-emitting element against the circuit board.

Next, an illumination device to which the present invention is appliedincorporates: a semiconductor light-emitting device including asemiconductor light-emitting element that includes: a laminatedsemiconductor layer in which a first semiconductor layer having a firstconduction type, a light-emitting layer and a second semiconductor layerhaving a second conduction type that is opposite to the first conductiontype are laminated in order; a first transparent electrode layer that isprovided on the laminated semiconductor layer, has transparency to lightemitted from the light-emitting layer and is crystalline; a secondtransparent electrode layer that is provided on the first transparentelectrode layer, has transparency to the light and is non-crystalline;and a reflecting layer that is provided on the second transparentelectrode layer and is reflective to the light; and a circuit board thatis arranged to face a side including the reflecting layer of thesemiconductor light-emitting element.

Further, an electronic apparatus to which the present invention isapplied incorporates: a semiconductor light-emitting device including asemiconductor light-emitting element that includes: a laminatedsemiconductor layer in which a first semiconductor layer having a firstconduction type, a light-emitting layer and a second semiconductor layerhaving a second conduction type that is opposite to the first conductiontype are laminated in order; a first transparent electrode layer that isprovided on the laminated semiconductor layer, has transparency to lightemitted from the light-emitting layer and is crystalline; a secondtransparent electrode layer that is provided on the first transparentelectrode layer, has transparency to the light and is non-crystalline;and a reflecting layer that is provided on the second transparentelectrode layer and is reflective to the light; and a circuit board thatis arranged to face a side including the reflecting layer of thesemiconductor light-emitting element.

Advantageous Effects of Invention

The semiconductor light-emitting element according to the presentinvention is capable of suppressing, by forming the crystalline firsttransparent electrode layer and the non-crystalline second transparentelectrode layer on the laminated semiconductor layer in which the n-typefirst semiconductor layer, the light-emitting layer and the p-typesecond semiconductor layer are laminated in this order, delaminationfrom the reflecting layer at the upper portion. Moreover, thesemiconductor light-emitting element according to the present inventionhas low forward voltage Vf, thereby capable of being a semiconductorlight-emitting element with large light emission output.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of a semiconductor light-emitting device to whichthe exemplary embodiment is applied;

FIG. 2 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of a semiconductor light-emitting element;

FIG. 3 is a diagram showing an example of a planar schematicconfiguration diagram of the semiconductor light-emitting element;

FIG. 4 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of a laminated semiconductor layer;

FIG. 5 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of a first electrode;

FIG. 6 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of a second electrode;

FIG. 7 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of another configuration of the second electrode;

FIG. 8 is a diagram showing bonding characteristics between a p-type GaNlayer (p-type semiconductor layer) and an IZO film (or Pt film); and

FIG. 9 is a schematic configuration diagram showing a result ofobservation through a transmission electron microscope (TEM) of a crosssection of crystalline IZO and amorphous IZO laminated on the laminatedsemiconductor layer.

DESCRIPTION OF EMBODIMENTS

An exemplary embodiment according to the present invention will bedescribed in detail below with reference to the accompanying drawings.

FIG. 1 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of a semiconductor light-emitting device 1 towhich the exemplary embodiment is applied.

The semiconductor light-emitting device 1 includes a semiconductorlight-emitting element 10 that emits light and a submount 15 as anexample of a circuit board on which wirings for supplying electric powerto the semiconductor light-emitting element 10 are provided and to whichthe semiconductor light-emitting element 10 is secured.

The semiconductor light-emitting element 10 includes: a substrate 110;an intermediate layer 120; a base layer 130; and a laminatedsemiconductor layer 100. The semiconductor light-emitting element 10also includes a first electrode 200 working as a positive electrode anda second electrode 300 working as a negative electrode, which are anexample of a pair of positive and negative connecting electrodes. Itshould be noted that the second electrode 300 is provided to a portionwhere a part of the laminated semiconductor layer 100 is cutout.

There is provided a protecting layer 180 that covers top and sidesurfaces of the intermediate layer 120, the base layer 130 and thelaminated semiconductor layer 100 except for a part of top surfaces ofthe first electrode 200 and the second electrode 300.

It should be noted that details of the semiconductor light-emittingelement 10 will be described later.

The submount 15 includes: a submount substrate 20; submount wirings 21and 24 that are provided on the submount substrate 20; and bumps 31 and34 as an example of a connector that electrically connects the firstelectrode 200 and the second electrode 300 of the semiconductorlight-emitting element 10 with the submount wirings 21 and 24,respectively.

In FIG. 1, the substrate 110 is located on an upper side of thesemiconductor light-emitting element 10. That is, the semiconductorlight-emitting element 10 is reversed and mounted on the submount 15. Toreverse and mount the semiconductor light-emitting element 10 on thesubmount 15 in this manner is referred to as flip-chip (FC) mounting orflip-chip (FC) bonding. This mounting system is also referred to asface-down (FD) mounting since the semiconductor light-emitting element10 is reversed to be mounted.

Description will be provided on light extraction in the exemplaryembodiment. Of the light emitted from the laminated semiconductor layer100 (specifically, a light-emitting layer 150 in FIG. 2, which will bedescribed later) of the semiconductor light-emitting element 10, lighttraveling toward the substrate 110 is extracted to the outside (upperdirection in FIG. 1). On the other hand, of the light emitted from thelight-emitting layer 150, light traveling toward the first electrode 200is reflected by a reflecting layer (a reflecting layer 220 b in FIG. 5,which will be described later) that shows high light reflectivity to thelight emitted from the light-emitting layer 150, proceeds toward thesubstrate 110, and is extracted to the outside (upper direction in FIG.1). There is also light extracted to the outside from the side surfaceof the laminated semiconductor layer 100, the intermediate layer 120 orthe base layer 130.

Hereinafter, detailed configuration of the submount 15 and thesemiconductor light-emitting element 10 will be described in this order.

(Submount)

In the submount 15, as the submount substrate 20, various kinds ofsubstrates which are insulative or conductive, such as a ceramicsubstrate, an MN (aluminum nitride) substrate, an Al (aluminum)substrate, a Cu (cupper) substrate and a glass epoxy substrate can beselected and used without any particular limitations.

It should be noted that, in the case where the conductive substrate suchas an Al substrate is used, at least one of the submount wirings 21 and24 is provided via an insulating layer for electrically insulating thesubmount wirings 21 and 24 from the submount substrate 20.

As the bumps 31 and 34 that connect the first electrode 200 and thesecond electrode 300 of the semiconductor light-emitting element 10 withthe submount wirings 21 and 24 of the submount substrate 20,respectively, Sn (tin)-added Au (Au—Sn alloy) balls or solder balls canbe used, for example. Especially, an Au—Sn alloy with a heatingtemperature of about 300° C. in connecting (contact bonding) ispreferred.

Hereinafter, detailed configuration of the semiconductor light-emittingelement 10 will be described.

(Semiconductor Light-Emitting Element)

FIG. 2 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of the semiconductor light-emitting element 10. InFIG. 1, the semiconductor light-emitting element 10 is reversed andmounted on the circuit board (submount) 15. In FIG. 2, description willbe given in the state where the semiconductor light-emitting element 10is not reversed to facilitate understanding. In other words, in FIG. 2,the substrate 110 is located to be on a lower side.

FIG. 3 is a diagram showing an example of a planar schematicconfiguration diagram of the semiconductor light-emitting element 10shown in FIG. 2. The planar diagram in FIG. 3 shows the semiconductorlight-emitting element 10 in FIG. 2 as viewed from the side of the firstelectrode 200 and the second electrode 300.

As shown in FIG. 2, the semiconductor light-emitting element 10includes: the substrate 110; the intermediate layer 120 laminated on thesubstrate 110; the base layer 130 laminated on the intermediate layer120; and the laminated semiconductor layer 100 laminated on the baselayer 130. The laminated semiconductor layer 100 includes: an n-typesemiconductor layer 140 as an example of a first semiconductor layer;the light-emitting layer 150 laminated on the n-type semiconductor layer140; and a p-type semiconductor layer 160, as an example of a secondsemiconductor layer, laminated on the light-emitting layer 150. Further,the semiconductor light-emitting element 10 includes the first electrode200 laminated on a surface 160 c of the p-type semiconductor layer 160.Still further, the semiconductor light-emitting element 10 includes thesecond electrode 300 laminated on a part of a semiconductor layerexposure surface 140 c of the n-type semiconductor layer 140 exposed bycutting a part of the p-type semiconductor layer 160, the light-emittinglayer 150 and the n-type semiconductor layer 160. Furthermore, thesemiconductor light-emitting element 10 includes the protecting layer180 provided to cover the top and side surfaces of the laminatedsemiconductor layer 100, the side surfaces of the intermediate layer 120and the base layer 130, and the top surfaces of the first electrode 200and the second electrode 300 except for a part of each thereof. Theprotecting layer 180 includes an opening 200 a provided to the firstelectrode 200 and an opening 300 a provided to the second electrode 300.The first electrode 200 and the second electrode 300 are connected tothe bumps 31 and 34, respectively, via the openings 200 a and 300 a.

In the semiconductor light-emitting element 10, the first electrode 200and the second electrode 300 are supposed to be the positive electrodeand the negative electrode, respectively, and the light-emitting layer150 emits light by passing a current through the laminated semiconductorlayer 100 (more specifically, the p-type semiconductor layer 160, thelight-emitting layer 150 and the n-type semiconductor layer 140) viathese electrodes.

Next, each constituent of the semiconductor light-emitting element 10will be described in more detail.

<Substrate>

As the substrate 110, there is no particular limitation on any substrateas long as group III nitride semiconductor crystals are epitaxiallygrown on a surface thereof, and accordingly, various kinds of substratecan be selected and used. However, as will be described later, since thesemiconductor light-emitting element 10 of the exemplary embodiment isFC-mounted so that the light is extracted from the substrate 110 side,it is preferable to have transparency to the light emitted from thelight-emitting layer 150. Accordingly, the substrate 110 composed of,for example, sapphire, zinc oxide, magnesium oxide, zirconium oxide,magnesium-aluminum oxide, gallium oxide, indium oxide, lithium-galliumoxide, lithium-aluminum oxide, neodium-gallium oxide,lanthanum-strontium-aluminum-tantalum oxide, strontium-titanium oxide,titanium oxide and the like can be used.

Moreover, among the above-described substrates, it is preferable to usethe sapphire substrate 110 whose (0001) surface (c-face) is a principalsurface. In the case where the sapphire substrate is used, theintermediate layer 120 (buffer layer) may be formed on the c-face of thesapphire.

<Intermediate Layer>

The intermediate layer 120 is preferably composed of polycrystalAl_(x)Ga_(1-x)N (0≦x≦1), and more preferably, composed of single crystalAl_(x)Ga_(1-x)N (0≦x≦1).

The intermediate layer 120 can be, for example, composed of polycrystalAl_(x)Ga_(1-x)N (0≦x≦1) with a thickness of 0.01 μm to 0.5 μm. If thethickness of the intermediate layer 120 is less than 10 nm, there aresome cases where an effect of the intermediate layer 120 to mediate thedifference in lattice constant between the substrate 110 and the baselayer 130 cannot be sufficiently obtained. On the other hand, if thethickness of the intermediate layer 120 is more than 0.5 μm, there is apossibility that the time of forming process of the intermediate layer120 becomes longer though there is no change to the function of theintermediate layer 120, and accordingly the productivity is decreased.

The intermediate layer 120 has a function of mediating the difference inlattice constant between the substrate 110 and the base layer 130 tofacilitate the formation of a single crystal layer which is C-axisoriented on the (0001) surface (c-face) of the sapphire of the substrate110. Consequently, if a single crystal base layer 130 is laminated onthe intermediate layer 120, the base layer 130 having more excellentcrystallinity can be laminated. It should be noted that the intermediatelayer forming process is preferably carried out in the presentinvention, but not necessarily needed.

Moreover, the crystal of the group III nitride semiconductorconstituting the intermediate layer 120 may have a single crystalstructure, and those having a single crystal structure are preferablyused. Crystals of the group III nitride semiconductor grow not only inan upper direction but also in an in-plane direction with respect to thesubstrate 110 to form a single crystal structure by controlling growingconditions. Accordingly, the intermediate layer 120 can be composed ofthe group III nitride semiconductor crystals having single crystalstructure by controlling layer forming conditions thereof. In the casewhere the intermediate layer 120 having such a single crystal structureis formed on the substrate 110, the buffer function of the intermediatelayer 120 effectively works, and thereby the group III nitridesemiconductor formed thereon becomes a crystal film having excellentorientation property and crystallinity.

Furthermore, it is possible to provide the group III nitridesemiconductor crystals constituting the intermediate layer 120 ascolumnar crystals (polycrystals) composed of an aggregate structurebased on hexagonal columns by controlling layer forming conditions. Itshould be noted that the columnar crystals composed of an aggregatestructure described here refers to crystals which are separated fromadjacent crystal grains by crystal grain boundaries formed therebetween,and are columnar by themselves in a longitudinal sectional shape.

<Base Layer>

As the base layer 130, Al_(x)Ga_(y)In_(z)N (0≦x≦1, 0≦y≦1, 0≦z≦1,x+y+z=1) can be used, but it is preferable to use Al_(x)Ga_(1-x)N(0≦x<1) because the base layer 130 with excellent crystallinity can beformed.

The thickness of the base layer 130 is preferably 0.1 μm or more, morepreferably 0.5 μm or more, and most preferably 1 μm or more. TheAl_(x)Ga_(1-x)N layer having excellent crystallinity is likely to beobtained with these layer thickness or more.

To improve the crystallinity of the base layer 130, it is desirable thatthe base layer 130 is not doped with impurities. However, ifconductivity of p-type or n-type is needed, p-type impurities or n-typeimpurities can be added.

<Laminated Semiconductor Layer>

The laminated semiconductor layer is composed of, for example, the groupIII nitride semiconductor, which is configured by laminating the n-typesemiconductor layer 140, the light-emitting layer 150 and the p-typesemiconductor layer 160 on the substrate 110 in this order as shown inFIG. 2.

Further, each of the n-type semiconductor layer 140, the light-emittinglayer 150 and the p-type semiconductor layer 160 may be configured byplural semiconductor layers.

Here, the n-type semiconductor layer 140 performs electrical conductionof a first conduction type in which an electron is a carrier, while thep-type semiconductor layer 160 performs electrical conduction of asecond conduction type in which a hole is a carrier.

It should be noted that the laminated semiconductor layer 100 withexcellent crystallinity can be obtained by forming by an MOCVD method,however, a sputtering method under optimized conditions can form thelaminated semiconductor layer 100 having more excellent crystallinitythan that formed by the MOCVD method. Hereinafter, descriptions will besequentially given.

<N-Type Semiconductor Layer>

FIG. 4 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of the laminated semiconductor layer 100. Then-type semiconductor layer 140 is preferably configured with ann-contact layer 140 a and an n-cladding layer 140 b. It should be notedthat the n-contact layer 140 a can also serve as the n-cladding layer140 b. Further, the above-described base layer 130 may be included inthe n-type semiconductor layer 140.

The n-contact layer 140 a is a layer for providing the second electrode300. The n-contact layer 140 a is preferably configured with theAl_(x)Ga_(1-x)N layer (0≦x<1, more preferably 0≦x≦0.5, and still morepreferably 0≦x≦0.1).

Further, the n-contact layer 140 a is preferably doped with n-typeimpurities, and preferably contains the n-type impurities having adensity of 1×10¹⁷/cm³ to 1×10²⁰/cm³, and preferably a density of1×10¹⁸/cm³ to 1×10¹⁹/cm³ on the point that a good ohmic contact with thesecond electrode 300 can be maintained. The n-type impurities are notparticularly limited, however, Si, Ge, Sn and so on are provided, and Siand Ge are preferably provided.

The thickness of the n-contact layer 140 a is preferably set to 0.5 μmto 5 μm, and more preferably set in a range of 1 μm to 3 μm. If thelayer thickness of the n-contact layer 140 a is in the above-describedranges, crystallinity of the semiconductor is suitably maintained.

It is preferable to provide the n-cladding layer 140 b between then-contact layer 140 a and the light-emitting layer 150. The n-claddinglayer 140 b performs injection of the carriers into the light-emittinglayer 150 and confinement of the carriers. The n-cladding layer 140 bcan be formed of AlGaN, GaN, GaInN and so on. The hetero junctionstructure or the superlattice structure in which the layer is laminatedplural times of these structures may also be used. When the n-claddinglayer 140 b is formed of GaInN, the band gap thereof is preferablylarger than that of GaInN of the light-emitting layer 150.

The thickness of the n-cladding layer 140 b is not particularly limited,but preferably in a range of 0.005 μm to 0.5 μm, and more preferably ina range of 0.005 μm to 0.1 μm. The impurity concentration of then-cladding layer 140 b is preferably in a range of 1×10¹⁷/cm³ to1×10²⁰/cm³, and more preferably in a range of 1×10¹⁸/cm³ to 1×10¹⁹/cm³.It is preferable to provide the impurity concentration in these rangesin terms of maintaining excellent crystallinity and reducing operationvoltage of the light-emitting element.

It should be noted that, in the case where the n-cladding layer 140 b isa layer containing the superlattice structure, the layer may contain astructure in which an n-side first layer composed of the group IIInitride semiconductor with a thickness of 10 nm or less and an n-sidesecond layer having a different composition from the n-side first layerand composed of the group III nitride semiconductor with a thickness of10 nm or less are laminated, though detailed illustration is omitted.

Further, the n-cladding layer 140 b may contain a structure in which then-side first layers and the n-side second layers are alternately andrepeatedly laminated, and the structure is preferably an alternatingstructure of GaInN and GaN or an alternating structure of GaInN havingdifferent compositions.

<Light-Emitting Layer>

As the light-emitting layer 150 laminated on the n-type semiconductorlayer 140, a single quantum well structure or a multiple quantum wellstructure can be employed.

As a well layer 150 b having a quantum well structure as shown in FIG.4, the group III nitride semiconductor layer composed of Ga_(1-y)In_(y)N(0<y<0.4) is usually used. The thickness of the well layer 150 b may bethe thickness by which quantum effects can be obtained, for example, 1nm to 10 nm, and is preferably 2 nm to 6 nm in terms of light emissionoutput.

Moreover, in the case of the light-emitting layer 150 having themultiple quantum well structure, the above-described Ga_(1-y)In_(y)N isemployed as the well layer 150 b, and Al_(z)Ga_(1-z)N (0≦z<0.3) having aband gap energy larger than that of the well layer 150 b is employed asa barrier layer 150 a. The well layer 150 b and the barrier layer 150 amay be doped or not doped with impurities depending upon a designthereof.

It should be noted that, in the exemplary embodiment, the light-emittinglayer 150 is configured to output blue light (light emission wavelengthof the order of λ=450 nm).

<P-Type Semiconductor Layer>

As shown in FIG. 4, the p-type semiconductor layer 160 is usuallyconfigured with the p-cladding layer 160 a and the p-contact layer 160b. Further, the p-contact layer 160 b can also serve as the p-claddinglayer 160 a.

The p-cladding layer 160 a performs confinement of carriers within thelight-emitting layer 150 and injection of carriers. The p-cladding layer160 a is not particularly limited as long as the band gap energy of thecomposition thereof is larger than that of the light-emitting layer 150and carriers can be confined within the light-emitting layer 150, but ispreferably composed of Al_(x)Ga_(1-x)N (0<x≦0.4).

It is preferable that the p-cladding layer 160 a is composed of suchAlGaN in terms of confinement of carriers within the light-emittinglayer 150. The thickness of the p-cladding layer 160 a is notparticularly limited, but preferably 1 nm to 400 nm, and more preferably5 nm to 100 nm.

The p-type impurity concentration of the p-cladding layer 160 a ispreferably 1×10¹⁸/cm³ to 1×10²¹/cm³, and more preferably 1×10¹⁹/cm³ to1×10²⁰/cm³. If the p-type impurity concentration is in the above ranges,excellent p-type crystals can be obtained without deterioratingcrystallinity.

Further, the p-cladding layer 160 a may have a superlattice structure inwhich the layer is laminated plural times of these structures, andpreferably has an alternating structure of AlGaN and AlGaN or analternating structure of AlGaN and GaN.

The p-contact layer 160 b is a layer for providing the first electrode200. The p-contact layer 160 b is preferably composed of Al_(x)Ga_(1-x)N(0≦x≦0.4). It is preferable that Al composition is in theabove-described range in terms of allowing to maintain excellentcrystallinity and good ohmic contact with the first electrode 200.

It is preferable to contain p-type impurities in a concentration of1×10¹⁸/cm³ to 1×10²¹/cm³, and preferably 5×10¹⁹/cm³ to 5×10²⁰/cm³ interms of maintaining good ohmic contact, suppressing cracking andmaintaining excellent crystallinity. The p-type impurities are notparticularly limited, but, for example, Mg is preferably provided.

The thickness of the p-contact layer 160 b is not particularly limited,but is preferably 10 nm to 500 nm, and more preferably 50 nm to 200 nm.It is preferable to provide the thickness of the p-contact layer 160 bin these ranges in terms of light emission output.

<First Electrode>

As shown in FIG. 2, the first electrode 200 is laminated on the topsurface 160 c of the p-type semiconductor layer 160. As shown in FIG. 3,in a planar view, the first electrode 200 (refer to FIG. 2) is formed tocover almost of all of the top surface 160 c of the p-type semiconductorlayer 160, except for a part that has been removed by etching or thelike so as to form the second electrode 300.

FIG. 5 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of the first electrode 200. The first electrode200 includes: a first transparent electrode layer 210; a reflectingsection 220 that reflects the light emitted from the light-emittinglayer 150; and an overcoat section 230 provided to cover the firsttransparent electrode layer 210 and the reflecting section 220. Thereflecting section 220 includes: a second transparent electrode layer220 a; a reflecting layer 220 b; and a first barrier layer 220 c. Theovercoat section 230 includes: a first bonding layer 230 a; a secondbarrier layer 230 b; a first metal layer 230 c; a second metal layer 230d; and a second bonding layer 230 e.

Hereinafter, descriptions will be given in order.

<First Transparent Electrode Layer>

It is preferable that the first transparent electrode layer 210 hastransparency to the light emitted from the light-emitting layer 150.Further, for uniformly passing a current over the entire surface of thep-type semiconductor layer 160, it is preferable to use the firsttransparent electrode layer 210 having excellent conductivity and narrowresistance distribution.

The first transparent electrode layer 210 is provided to preventelements of the reflecting layer 220 b, which will be described later,from moving (migrating) into the laminated semiconductor layer 100.

It is preferable that the first transparent electrode layer 210 canobtain an ohmic contact with the p-type semiconductor layer 160 and hassmall contact resistance. Consequently, it is preferable that the firsttransparent electrode layer 210 is crystalline.

As an example of the first transparent electrode layer 210, an oxideconductive material having excellent optical transparency to the lightof a wavelength emitted from the light-emitting layer 150 is used. Inparticular, an oxide conductive material containing any one of In(indium) and Ti (titanium) is used. A part of oxides containing In or Tiis preferable in the point that both optical transparency andconductivity thereof are superior to other transparent conductive films.Examples of conductive oxides containing In include: IZO (indium zincoxide (In₂O₃—ZnO)); ITO (indium tin oxide (In₂O₃—SnO₂)); IGO (indiumgallium oxide (In₂O₃—Ga₂O₃)); and ICO (indium cerium oxide(In₂O₃—CeO₂)). It should be noted that a dopant such as fluorine may beadded to these materials. Further, examples of conductive oxidescontaining Ti include titanium oxide or the like, and titanium oxideadded with niobium (Nb) is exemplified.

As described above, it is preferable that the first transparentelectrode layer 210 is crystalline. The first transparent electrodelayer 210 may be crystallized by performing thermal annealing.

The first transparent electrode layer 210 can be formed by providingthese materials by any well-known method in this technical field.

In the exemplary embodiment, as the first transparent electrode layer210, a transparent material containing In₂O₃ crystals having a crystalstructure of a hexagonal system or a bixbyite structure (for example,ITO or IZO) can be preferably used.

For instance, in the case where IZO containing In₂O₃ crystals having acrystal structure of a hexagonal system is used as the first transparentelectrode layer 210, an amorphous (non-crystalline) IZO film that has anexcellent etching property can be used and processed into a specificshape, and thereafter, processed into the first transparent electrodelayer 210 that is crystalline by transferring the amorphous state into astructure containing crystals through a heat treatment or the like.

Further, as the IZO film used for the first transparent electrode layer210, it is preferable to employ a composition showing the lowestspecific resistance.

For example, a ZnO concentration in IZO is preferably 1% by mass to 20%by mass, and more preferably in a range of 5% by mass to 15% by mass.10% by mass is especially preferred. Moreover, the thickness of the IZOfilm is preferably in a range of 5 nm to 500 nm so as not to absorb thelight emitted from the light-emitting layer 150.

The IZO film used as the first transparent electrode layer 210 is, as anexample, processed into the shape of the pattern I shown in FIGS. 3 and5. It is preferable to perform the patterning prior to a heat treatmentdescribed later. Since the IZO film in the amorphous state is changedinto the crystallized IZO film by a heat treatment, it becomes difficultto apply etching thereto compared to the IZO film in the amorphousstate. In contrast, the IZO film prior to the heat treatment is in theamorphous state, and thereby it is possible to apply etching theretowith ease and good accuracy by use of a known etchant (ITO-07N etchantmanufactured by KANTO CHEMICAL CO., INC).

Etching for the IZO film in the amorphous state may be performed byusing a dry-etching apparatus. On that occasion, Cl₂, SiCl₄, BCl₃ or thelike can be used as an etching gas. The IZO film in the amorphous statecan be changed into an IZO film containing In₂O₃ crystals having acrystal structure of a hexagonal system or an IZO film containing In₂O₃crystals having a bixbyite structure by performing a heat treatment of,for example, 500° C. to 1000° C. and controlling the conditions. Sinceit is difficult to apply etching to the IZO film containing In₂O₃crystals having a crystal structure of a hexagonal system as describedabove, the heat treatment is preferably performed after theaforementioned etching process.

The heat treatment of the IZO film used for the first transparentelectrode layer 210 is desirably performed in an atmosphere notcontaining O₂, and as the atmosphere not containing O₂, an inert gasatmosphere such as N₂ atmosphere or a mixed gas atmosphere of H₂ and aninert gas such as N₂ can be provided, and accordingly, the N₂ atmosphereor the mixed gas atmosphere of N₂ and H₂ is desirable. It should benoted that, if the heat treatment of the IZO film is performed in the N₂atmosphere or the mixed gas atmosphere of N₂ and H₂, it is possible to,for example, crystallize the IZO film into a film containing In₂O₃crystals having a crystal structure of a hexagonal system andeffectively reduce a sheet resistance of the IZO film.

Further, the heat treatment temperature of the IZO film is preferably500° C. to 1000° C. If the heat treatment is performed at a temperatureless than 500° C., a possibility occurs that the IZO film cannot becrystallized sufficiently, thus, in some cases optical transparency ofthe IZO film is not sufficiently high. If the heat treatment isperformed at a temperature more than 1000° C., the IZO film iscrystallized but sometimes the optical transparency of the IZO film isnot sufficiently high. Further, if the heat treatment is performed at atemperature more than 1000° C., there is a possibility of deterioratingthe semiconductor layer provided below the IZO film.

In the case of crystallizing the IZO film in an amorphous state,differences in layer forming conditions or heat treatment conditionsresult in a difference in a crystal structure of the IZO film. However,in the exemplary embodiment according to the present invention, thefirst transparent electrode layer 210 may be, particularly in the caseof crystalline IZO, IZO containing In₂O₃ crystals having a bixbyitecrystal structure or IZO containing In₂O₃ crystals having a crystalstructure of a hexagonal system. Particularly, IZO containing In₂O₃crystals having a crystal structure of a hexagonal system is preferred.

Especially, as described above, the IZO film crystallized by the heattreatment shows better adhesiveness to the p-type semiconductor 160 andavailability of good ohmic contact than those of the IZO film in anamorphous state, thus being very effective in the exemplary embodimentaccording to the present invention. Moreover, since the resistance isreduced in the IZO film crystallized by the heat treatment compared tothat in the IZO film in an amorphous state, the IZO film crystallized bythe heat treatment is preferred in the point that the forward voltage Vfcan be reduced when the semiconductor light-emitting element 10 isconfigured.

<Reflecting Section>

Next, configuration of the reflecting section 220 will be described. Thereflecting section 220 includes: the second transparent electrode layer220 a; the reflecting layer 220 b; and the first barrier layer 220 c. Aswill be described later, these layers are a group of layers successivelyformed.

It is preferable that the second transparent electrode layer 220 a canobtain ohmic contact with each of the first transparent electrode layer210 and the reflecting layer 220 b and has small contact resistance. Inaddition, it is preferable that the second transparent electrode layer220 a has transparency to the light emitted from the light-emittinglayer 150.

It is preferable that the reflecting layer 220 b indicates excellentreflective characteristics to the light emitted from the light-emittinglayer 150.

<Second Transparent Electrode Layer>

The second transparent electrode layer 220 a is a layer for ensuringadhesiveness between the first transparent electrode layer 210 and thereflecting layer 220 b. In other words, if the first transparentelectrode layer 210 is crystallized by the heat treatment, there is apossibility that the reflecting layer 220 b described later is notdeposited but is delaminated. Accordingly, it is preferable that thesecond transparent electrode layer 220 a is non-crystalline (amorphous).Consequently, it is preferable to form the second transparent electrodelayer 220 a after crystallizing the first transparent electrode layer210 by the heat treatment or the like. This is because, if the secondtransparent electrode layer 220 a is laminated subsequent to the firsttransparent electrode layer 210 and then the heat treatment is carriedout for crystallizing the first transparent electrode layer 210, thereis a possibility that the second transparent electrode layer 220 a isalso crystallized.

In the exemplary embodiment, similar to the first transparent electrodelayer 210, a transparent material containing In₂O₃ crystals (such asIZO, ITO and the like) can be preferably used as the second transparentelectrode layer 220 a.

Further, in the case where the IZO film is used as the secondtransparent electrode layer 220 a and the IZO film is also used as thefirst transparent electrode layer 210, a ZnO concentration in IZO may bethe same.

For example, the ZnO concentration in IZO is preferably 1% by mass to20% by mass, and more preferably in a range of 5% by mass to 15% bymass. 10% by mass is especially preferred. Further, the thickness of theIZO film is preferably in a range of 1 nm to 5 nm so as not to absorbthe light emitted from the light-emitting layer 150.

In the case of using ITO as the second transparent electrode layer 220a, an SnO₂ concentration is used approximately on the same level as therange of concentration of the aforementioned IZO, and the range of thethickness is also on the same level.

The second transparent electrode layer 220 a is processed into the shapeof the pattern II shown in FIGS. 3 and 5. This patterning may be carriedout by a lift-off method. In this case, on the first transparentelectrode layer 210, a pattern (not shown) by a resist film with thepattern II as an opening portion is formed. It should be noted that itis preferable to form a wall surface of the resist film of the openingportion into a reverse-tapered shape. Thereafter, on the resist film,the second transparent electrode layer 220 a of the IZO film, thereflecting layer 220 b of an Ag film described later, and the firstbarrier layer 220 c of a Ta film, which is similarly described later,are successively laminated in this order by a sputtering method or thelike. On this occasion, sputtering conditions or the like are set sothat the second transparent electrode layer 220 a of the IZO film is inthe amorphous state.

After that, the IZO film, the Ag film and the Ta film on the resist filmwith the pattern II as the opening portion are removed together with theresist film to form the second transparent electrode layer 220 a, thereflecting layer 220 b and the first barrier layer 220 c. By doing thisway, the central portion of each of the second transparent electrodelayer 220 a, the reflecting layer 220 b and the first barrier layer 220c has a certain thickness and is formed almost flat, whereas, thethickness of the end portion of each layer is gradually reduced and thelayers can be formed so that the end portion of a lower layer is coveredwith the end portion of an upper layer.

[Reflecting Layer]

As the material of the reflecting layer 220 b, there is no particularlimitation, but the material may indicate excellent reflectivecharacteristics to the light generated by the light-emitting layer 150of the semiconductor light-emitting element 10. It should be noted that,since the reflecting layer 220 b constitutes a part of the firstelectrode 200, it is preferable that the reflecting layer 220 b hasexcellent conductivity. For these reasons, a metal such as Ag, Al, Niand the like or a metal alloy containing at least one of them ispreferred. Among them, Ag or an alloy containing Ag can be preferablyused.

As described above, the Ag film used as the reflecting layer 220 b canbe provided by any well-known method in this technical field, such as asputtering method.

Further, the thickness of the Ag film used as the reflecting layer 220 bis preferably in a range of 50 nm to 5000 nm so as not to allow thelight emitted by the light-emitting layer 150 to pass through.Especially, the thickness is more preferably in a range of 80 nm to 1200nm. It should be noted that, if the thickness of the reflecting layer220 b is less than 50 nm, there are some cases that are not preferablein terms of deterioration of reflective performance of the light emittedfrom the light-emitting layer 150.

[First Barrier Layer]

The first barrier layer 220 c is a layer for suppressing movement(migration) of elements that form the reflecting layer 220 b into thefirst metal layer 230 c of the overcoat section 230, which will bedescribed later, and conversely, migration of elements that form thefirst metal layer 230 c into the reflecting layer 220 b.

As the first barrier layer 220 c, it is preferable to employ those thatcan make an ohmic contact with the reflecting layer 220 b and has smallcontact resistance with the reflecting layer 220 b. However, the firstbarrier layer 220 b is not required to have a function for transmittingthe light from the light-emitting layer 150 in principle, andaccordingly, as distinct from the above-described first transparentelectrode layer 210, there is no need to have optical transparency.Further, since the first barrier layer 220 c has a function for feedingto the p-type semiconductor layer 160 through the reflecting layer 220 band the first transparent electrode layer 210, it is preferable to usethose having excellent conductivity and narrow resistance distribution.

The first barrier layer 220 c is not particularly limited; however, itmay be only necessary for the first barrier layer 220 c to suppressmigration of the materials of the reflecting layer 220 b and the firstmetal layer 230 c that constitutes the overcoat section 230.

In the exemplary embodiment, as the first barrier layer 220 c, Ta, Ti,Ni, Nb or W can be used. In particular, Ta can be preferably used.Further, the first barrier layer 220 c (for example, the Ta film) can beprovided by any well-known method in this technical field, such as thesputtering method.

Moreover, the thickness of the first barrier layer 220 c (for example,the Ta film) is preferably in a range of 20 nm to 100 nm. Especially,the thickness is more preferably in a range of 30 nm to 70 nm.

<Overcoat Section>

Next, configuration of the overcoat section 230 will be described.

The overcoat section 230 includes: the first bonding layer 230 a; thesecond barrier layer 230 b; the first metal layer 230 c; the secondmetal layer 230 d; and the second bonding layer 230 e. As will bedescribed later, these layers constitute a group of layers successivelyformed. Hereinafter, these will be described.

[First Bonding Layer]

The first bonding layer 230 a is provided at a lowermost layer, which isa layer for bonding the reflecting section 220 and the overcoat section230.

As the first bonding layer 230 a, there is no particular limitation, butthose indicating excellent bonding characteristics with the firstbarrier layer 220 c provided at an uppermost layer of the reflectingsection 220 are preferred.

In the case where Ta is used as the first barrier layer 220 c as in theexemplary embodiment, Ta, an alloy containing Ta, or a compound of Tahaving conductivity is preferred. In particular, TaN (tantalum nitride)can be preferably used.

The thickness of the first bonding layer 230 a (for example, the TaNfilm) is preferably in a range of 1 nm to 50 nm. The first bonding layer230 a can be formed by any well-known method in this technical field.

It should be noted that there may be no first bonding layer 230 a if thebonding characteristics between the first barrier layer 220 c and thesecond barrier layer 230 b are excellent.

The first bonding layer 230 a (for example, the TaN film) is processedinto a shape of the pattern III shown in FIGS. 3 and 5. The pattern IIIis slightly broader than the pattern II, and the first bonding layer 230a is provided to cover the reflecting section 220 that is formed intothe shape of the pattern II. This patterning may be performed by thelift-off method. In this case, on the first transparent electrode layer210, a resist film (not shown) having an opening portion of the patternIII is formed. It should be noted that it is preferable to form a wallsurface of the resist film of the opening portion into a reverse-taperedshape. Thereafter, on the resist film, the first bonding layer 230 a(for example, the TaN film), and the second barrier layer 230 b (forexample, the Ta film), the first metal layer 230 c (for example, a Ptfilm), the second metal layer 230 b (for example, an Au film) and thesecond bonding layer (for example, the Ta film), which will be describedlater, are successively laminated in this order by a sputtering methodor the like.

Thereafter, above-described films laminated on the resist film areremoved together with the resist film to form the first bonding layer230 a, the second barrier layer 230 b, the first metal layer 230 c, thesecond metal layer 230 d and the second bonding layer 230 e.

By doing this way, as shown in FIG. 5, the central portion of each ofthe first bonding layer 230 a, the second barrier layer 230 b, the firstmetal layer 230 c, the second metal layer 230 d and the second bondinglayer 230 e has a certain thickness and is formed almost flat, whereas,the thickness of the end portion of each layer is gradually reduced andthe layers can be formed so that the end portion of a lower layer iscovered with the end portion of an upper layer.

[Second Barrier Layer]

The second barrier layer 230 b is a layer for suppressing migration ofelements that form the first metal layer 230 c into the reflecting layer220 b, and conversely, migration of elements that form the reflectinglayer 220 b into the first metal layer 230 c. The action of the secondbarrier layer 230 b is similar to that of the first barrier layer 220 c.Accordingly, similar to the first barrier layer 220 c, Ta, Ti, Ni, Nb orW can be used as the second barrier layer 230 b, and in particular, Tacan be preferably used. The second barrier layer 230 b (for example, theTa film) can be provided by any well-known method in this technicalfield, such as a sputtering method, as described above.

Further, the thickness of the Ta film used as the second barrier layer220 c is preferably in a range of 20 nm to 100 nm. Especially, thethickness is more preferably in a range of 30 nm to 70 nm.

As described above, since the second barrier layer 230 b is provided toa range of the pattern III, which is broader than the pattern II,contact between the reflecting layer 220 b and the first metal layer 230c described later can be suppressed.

[First Metal Layer]

The first metal layer 230 c is provided to improve adhesiveness betweenthe second metal layer 230 d of Au or the like, which will be describedlater, and the second barrier layer 230 b.

As the bumps 31 and 34, an Au ball or a solder boll is used. Then, it ispreferable that Au or an Au alloy is present on the surface of the firstelectrode 200 (second metal layer 230 d) that is connected to the bump31. For this reason, in particular, a Pt film can be preferably used asthe first metal layer 230 c. As described above, the first metal layer230 c (for example, a film of Pt, Hf, Ir, Os, Rh or W) can be providedby any well-known method in this technical field, such as a sputteringmethod.

Further, the thickness of the first metal layer 230 c is preferably in arange of 50 nm to 200 nm. Especially, the thickness is more preferablyin a range of 70 nm to 150 nm.

[Second Metal Layer]

The second metal layer 230 d is, as described later, connected to thebump 31. As a material for the second metal layer 230 d, Au, Al, Ni, Cuor a metal alloy containing at least one of them is preferred. Amongthem, Au, Al or a metal alloy containing at least one of them can bepreferably used. Since Au and Al are metals having excellentadhesiveness with an Au alloy which is often used as bumps, use of Au,Al or a metal alloy containing at least one of them enables adhesivenesswith the bumps to be excellent. Among them, Au or an Au alloy isespecially desirable. As described above, the Au film or the like usedas the second metal layer 230 d can be provided by any well-known methodin this technical field, such as a sputtering method.

Further, the thickness of the second metal layer 230 d is preferably ina range of 50 nm to 2000 nm. Especially, the thickness is morepreferably in a range of 200 nm to 1500 nm.

If the second metal layer 230 d is too thin, the adhesiveness with thebump 31 is deteriorated; if too thick, there are no advantages and onlythe increase in cost is caused. Further, according to thecharacteristics of the bonding pad, the thicker the second metal layer230 d is, the higher the adhesiveness with the bump 31 becomes, which ispreferred. Therefore, it is more preferable that the thickness of thesecond metal layer 230 d is 200 nm or more. Moreover, in terms of theproduction costs, the thickness is preferably 200 nm or less.

[Second Bonding Layer]

The second bonding layer 230 e is provided for ensuring adhesivenessbetween the second metal layer 230 d and the protecting layer 180.

As described above, if the second metal layer 230 d is Au and theprotecting layer 180 is SiO₂ as in the exemplary embodiment, theadhesiveness between the second metal layer 230 d and the protectinglayer 180 are poor. To improve bonding characteristics, a metal such asTa, Ti, Cr, Mo, Ni or W or an alloy containing at least one of them canbe preferably used.

Next, the second electrode 300 will be described.

<Second Electrode>

As shown in FIG. 2, the second electrode 300 is formed on thesemiconductor layer exposure surface 140 c of the n-type semiconductorlayer 140. In forming the second electrode 300 in this way, then-contact layer 140 a (refer to FIG. 2) of the n-type semiconductorlayer 140 is exposed by cutting and removing a part of thelight-emitting layer 150 and the p-type semiconductor layer 160 by amethod such as etching, and then the second electrode 300 is formed onthe semiconductor layer exposure surface 140 c that has been obtained.

FIG. 6 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of the second electrode 300. The second electrode300 corresponds to the reflecting section 220 and the overcoat section230 in the first electrode 200 shown in FIG. 5. In other words, thesecond electrode 300 has the same configuration as the first electrode200 except for the first transparent electrode layer 210. Consequently,same symbols are assigned and detailed description is omitted.

In this case, layers in the first electrode 200 and the second electrode300 provided above the second transparent electrode layer 220 aconstitute the reflecting section 220 and the overcoat section 230, andhave the same configuration. Accordingly, after the first transparentelectrode layer 210 is formed, the second electrode 300 can be formed bythe same process of the first electrode 200.

FIG. 7 is a diagram showing an example of a cross-sectional schematicconfiguration diagram of another configuration of the second electrode300. In this second electrode 300, the second transparent electrodelayer 220 a and the reflecting layer 220 b shown in FIG. 6 are replacedwith a third metal layer 220 d. However, the configuration of theovercoat section 230 is the same as that of the first electrode 200.

It is preferable that the third metal layer 220 d can obtain an ohmiccontact with the n-type semiconductor layer 140 and has small contactresistance. As the third metal layer 220 d, a metal such as Al or Alalloy can be preferably used.

In this case, the first electrode 200 and the second electrode 300 aredifferent except for the overcoat section 230, and therefore, requiredifferent processes to be formed. It should be noted that the overcoatsection 230 can be formed at the same time.

Of the light emitted from the light-emitting layer 150, the lighttraveling toward the first electrode 200 is reflected by the reflectinglayer 220 b and travels toward the substrate 110. However, a part of thelight is diffused to travel in a lateral direction or a diagonaldirection. Moreover, the light also travels in the direction of thesecond electrode 300. Consequently, it is preferable that the secondelectrode 300 includes the reflecting layer 220 b, and thereby capableof improving the light extraction efficiency. It should be noted that,even in the case of using the third metal layer 220 d, it is preferableto configure the third metal layer 220 d with a material having highreflectance to the light emission wavelength.

<Protecting Layer>

Further, in the exemplary embodiment, the protecting layer 180 made ofsilicon oxide such as SiO₂ or nitride such as Si₃N₄ may be formed tocover the top surface 160 c of the p-type semiconductor layer 160, thetop surface of the semiconductor layer exposure surface 140 c of then-type semiconductor layer 140 (including the side wall subjected toetching) and surfaces of the first electrode 200 and the secondelectrode 300 except for a part thereof (the opening 200 a and theopening 300 a).

Accordingly, except for the part of the surfaces of the first electrode200 and the second electrode 300 (the opening 200 a and the opening 300a), it is possible to shield the semiconductor light-emitting element 10to significantly reduce the possibility of entry of external air orwater into the semiconductor light-emitting element 10, as well as tocontribute to suppressing delamination of the first electrode 200 andthe second electrode 300 of the semiconductor light-emitting element 10.

The thickness of the protecting layer 180 is preferably in a range of 50nm to 1000 nm, more preferably in a range of 100 nm to 500 nm, and stillmore preferably in a range of 150 nm to 450 nm.

By setting the thickness of the protecting layer 180 to the range of 50nm to 1000 nm, the possibility of entry of external air or water intothe light-emitting layer 150 of the semiconductor light-emitting element10 is significantly reduced, and thereby delamination of the firstelectrode 200 and the second electrode 300 of the semiconductorlight-emitting element 10 can be suppressed.

In the forming method of the protecting layer 180, for example, in thefirst place, the protecting layer 180 composed of SiO₂ is formed on thetop surface 160 c of the p-type semiconductor layer 160, the top surfaceof the semiconductor layer exposure surface 140 c of the n-typesemiconductor layer 140 (including the side wall subjected to etching)and surfaces of the first electrode 200 and the second electrode 300,and thereafter, a resist not shown in the figure is applied on theprotecting layer 180.

Then, the resist on the part of the surfaces of the first electrode 200and the second electrode 300 (the opening 200 a and the opening 300 a)is removed and the protecting layer 180 and the second bonding layer 230e are removed by a known etching method to form the opening 200 a andthe opening 300 a on the surface of the second metal layer 230 d of eachelectrode.

The opening 200 a of the first electrode 200 can be formed anywhere onthe first electrode 200.

Accordingly, for example, the opening 200 a of the first electrode 200may be formed at a position farthest from the opening 300 a of thesecond electrode 300, or formed at a center of the semiconductorlight-emitting element 10. However, it is not preferable to form theopening 200 a at a position too close to the opening 300 a of the secondelectrode 300 because a short is caused between the bumps 31 and 34.

Further, the work of the flip-chip bonding can be conducted easier ifthe opening 200 a of the first electrode 200 is larger as an area;however, it is preferable that the opening 200 a is of the extentslightly larger than the diameter of the bump 31. For example, it ispreferable to form the opening 200 a as a circle with a diameter of theorder of 100 μm, but not necessarily be a circle. The same is true onthe opening 300 a of the second electrode 300.

Next, description will be given to an example of a method for producingthe semiconductor light-emitting device 1 shown in FIG. 1. Incidentally,suppose that, in the second electrode 300 as a negative electrode, thereflecting section 220 and the overcoat section 230 employ the sameconfiguration (the configuration shown in FIG. 6) as that of the firstelectrode 200.

(Method for Producing Semiconductor Light-Emitting Element)

First, a method for producing the semiconductor light-emitting element10 in the exemplary embodiment will be described.

The semiconductor light-emitting element 10 includes: an intermediatelayer forming process in which the intermediate layer 120 is formed onthe substrate 110; a base layer forming process in which the base layer130 is formed; a process for forming the laminated semiconductor layer100 including the light-emitting layer 150; a process for forming thesemiconductor layer exposure surface 140 c by cutting out a part of thelaminated semiconductor layer 100; and an electrode forming process inwhich the first electrode 200 is formed and the second electrode 300 isformed on the semiconductor layer exposure surface 140 c.

Here, the process for forming the laminated semiconductor layer 100including the light-emitting layer 150 includes: an n-type semiconductorlayer forming process in which the n-type semiconductor layer 140 isformed; a light-emitting layer forming process in which thelight-emitting layer 150 is formed; and a p-type semiconductor layerforming process in which the p-type semiconductor layer 160 is formed.

In some cases, the method for producing the semiconductor light-emittingelement 10, to which the exemplary embodiment is applied, includes anannealing process after the electrode forming process, in which heattreatment is applied to the semiconductor light-emitting element 10 thathas been obtained, as necessary.

Hereafter, each process will be described in turn.

<Intermediate Layer Forming Process>

First, the substrate 110 is subjected to preprocessing for forming theintermediate layer 120. The preprocessing can be performed by a methodof, for example, placing the substrate 110 in a chamber of a sputteringdevice and conducting sputtering before forming the intermediate layer120. Specifically, preprocessing for cleaning the top surface of thesubstrate 110 by exposing thereof in plasma of Ar or N₂ may beperformed. Organic substances or oxides adhered to the top surface ofthe substrate 110 can be removed by the action of plasma of Ar gas or N₂gas on the substrate 110.

Next, on the top surface of the substrate 110, the intermediate layer120 is laminated by the sputtering method.

In the case of forming the intermediate layer 120 having a singlecrystal structure by the sputtering method, as for the ratio of a flowrate of nitrogen to a flow rate of nitrogen materials and inert gases inthe chamber, the nitrogen materials desirably account for 50 vol % to100 vol %.

Further, in the case of forming the intermediate layer 120 havingcolumnar crystals (polycrystals) by the sputtering method, as for theratio of the flow rate of nitrogen to the flow rate of nitrogenmaterials and inert gases in the chamber, the nitrogen materialsdesirably account for 1 vol % to 50 vol %. It should be noted that theintermediate layer 120 can be formed not only by the sputtering method,but also by the MOCVD method.

<Base Layer Forming Process>

Next, after forming the intermediate layer 120, the base layer 130 of asingle crystal is formed on the top surface of the substrate 110 onwhich the intermediate layer 120 has been formed. The base layer 130 maybe formed by the sputtering method or the MOCVD method.

<Laminated Semiconductor Layer Forming Process>

The laminated semiconductor layer forming process includes the n-typesemiconductor layer forming process, the light-emitting layer formingprocess and the p-type semiconductor layer forming process.

<N-Type Semiconductor Layer Forming Process>

After forming the base layer 130, the n-type semiconductor layer 140 isformed by laminating the n-contact layer 140 a and the n-cladding layer140 b. The n-contact layer 140 a and the n-cladding layer 140 b may beformed by the sputtering method or the MOCVD method.

<Light-Emitting Layer Forming Process>

Formation of the light-emitting layer 150 may be performed by eithermethod of sputtering or MOCVD, but especially, the MOCVD method ispreferred. Specifically, the barrier layers 150 a and the well layers150 b may be alternately and repeatedly laminated such that the barrierlayers 150 a are located to face the n-type semiconductor layer 140 andthe p-type semiconductor layer 160.

<P-Type Semiconductor Layer Forming Process>

Further, formation of the p-type semiconductor layer 160 may beperformed by either method of sputtering or MOCVD. Specifically, thep-cladding layers 160 a and the p-contact layers 160 b may be laminatedin turn.

<First Transparent Electrode Layer Forming Process>

The first transparent electrode layer 210 is formed by known methods offilm formation by the sputtering method or the like, resist patternformation corresponding to the pattern I in FIGS. 3 and 5 byphotolithography or the like and subsequent etching.

<Semiconductor Layer Exposure Surface Forming Process>

The semiconductor layer exposure surface 140 c is formed by etching apart of the laminated semiconductor layer 100, and exposing a part ofthe n-contact layer 140 a.

<Heat Treatment Process>

Then, under the reducing atmosphere such as nitrogen, heat treatment isperformed in a range of 500° C. to 1000° C. This heat treatment isperformed for crystallizing the first transparent electrode layer 210and increasing the bonding characteristics between the p-typesemiconductor layer 160 and the first transparent electrode layer 210.

<First Electrode and Second Electrode Forming Process>

Next, a resist film having an opening of the pattern II shown in FIGS. 3and 5 on the first transparent electrode layer 210 and an opening of thepattern IV shown in FIGS. 3 and 6 on the semiconductor layer exposuresurface 140 c is formed. Then the second transparent electrode layer 220a, reflecting layer 220 b, and the first barrier layer 220 c are formedby the sputtering method or the like in this order (each process isreferred to as the second transparent electrode layer forming process,the reflecting layer forming process and the first barrier formingprocess). It should be noted that it is preferable to continuously formthe second transparent electrode layer 220 a, the reflecting layer 220 band the first barrier layer 220 c without breaking a vacuum state interms of adhesiveness or contamination, and thereby capable of reducingthe time for film formation.

Thereafter, the resist film and materials deposited thereon, which aresame as the second transparent electrode layer 220 a, the reflectinglayer 220 b and the first barrier layer 220 c, are delaminated andremoved by being immersed in a resist removal solution.

Similarly, a resist film having an opening of the pattern III shown inFIGS. 3 and 5 on the first transparent electrode layer 210 and anopening of the pattern V shown in FIGS. 3 and 6 on the semiconductorlayer exposure surface 140 c is formed. Then the first bonding layer 230a, the second barrier layer 230 b, the first metal layer 230 c, thesecond metal layer 230 d and the second bonding layer 230 e arecontinuously formed by the sputtering method or the like. It should benoted that it is preferable to continuously form the first bonding layer230 a, the second barrier layer 230 b, the first metal layer 230 c, thesecond metal layer 230 d and the second bonding layer 230 e withoutbreaking a vacuum state in terms of adhesiveness or contamination, andthereby capable of reducing the time for film formation.

Thereafter, the resist film and materials deposited thereon, which aresame as the first bonding layer 230 a, the second barrier layer 230 b,the first metal layer 230 c, the second metal layer 230 d and the secondbonding layer 230 e, are delaminated and removed by being immersed in aresist removal solution (an overcoat section forming process).

It should be noted that, in forming the layers by the sputtering methodor the like as described above, sputtering conditions are set so thatthe second transparent electrode layer 220 a is in the amorphous state.

Finally, the protecting layer 180 is formed to cover the surfaces sidefaces of the intermediate layer 120, the base layer 130, the laminatedsemiconductor layer 100, the semiconductor layer exposure surface 140 c,the first electrode 200 and the second electrode 300, and thereafter, aresist not shown in the figure is applied on the protecting layer 180.

Then, to be connected to the bumps 31 and 34, the protecting layer 180and the second bonding layer 230 e corresponding to the part of theopening 200 a and the opening 300 a are removed by RIE (reactive ionetching) or the like to expose the surface of the second metal layer 230d of the first electrode 200 and the second electrode 300.

In the exemplary embodiment, the reflecting section 220 and the overcoatsection 230 in the first electrode 200 and the second electrode 300 havethe same configuration, and accordingly, productivity of thesemiconductor light-emitting element 10 is improved.

(Method for Producing Submount)

Next, the method for producing the submount 15 will be described.

The submount substrate 20 of ceramic or the like is prepared, and thesubmount wirings 21 and 24 made of Ag or Au are formed by the lift-offmethod or the like. Then, except for the parts that connect to the firstelectrode 200 and the second electrode 300 of the semiconductorlight-emitting element 10, namely, the parts on which the bumps 31 and34 are formed, the surface of the submount substrate 20 is covered witha protecting film made of SiO₂ by the lift-off method or the like.Finally, the ball-shaped bumps 31 and 34 made of an Au—Sn alloy areprovided.

(Method for Producing Semiconductor Light-Emitting Device)

Lastly, the method for producing the semiconductor light-emitting device1 will be described.

The semiconductor light-emitting element 10 is arranged face down on thesubmount 15, and the semiconductor light-emitting element 10 and thesubmount 15 are aligned so that the bumps 31 and 34 on the submount 15and the first electrode 200 and the second electrode 300 of thesemiconductor light-emitting element 10 correspond to each other basedon the predetermined connective relationship (alignment process).

After that, the semiconductor light-emitting element 10 is pressed(fixed by pressure) against the submount 15 while being heated at 300°C. (heating and pressing process). Consequently, the bumps 31 and 34 areelectrically connected to the first electrode 200 and the secondelectrode 300, respectively.

In this manner, the semiconductor light-emitting device 1 is completed.

By the way, in the exemplary embodiment, the first transparent electrodelayer 210, which is crystalline, and the second transparent electrodelayer 220 a, which is amorphous (non-crystalline), are laminated in thefirst electrode 200 provided on the p-type semiconductor layer 160.

The reason why the first transparent electrode layer 210 is made to becrystalline is to improve the adhesiveness (bonding characteristics)between the p-type GaN layer, which is the p-type semiconductor layer160, and the first transparent electrode layer 210 (for example, the IZOfilm), as will be described later. For example, in the case where theIZO is not crystallized, the forward voltage Vf becomes high compared tothe case of crystallizing.

The reason why the second transparent electrode layer 220 a, which isamorphous, is provided is that, when the reflecting layer 220 b (forexample, the Ag film) is formed on a crystallized film (IZO film), whichis the first transparent electrode layer 210, the reflecting layer 220 b(Ag film) is delaminated from the first transparent electrode layer 210(IZO film). The reflecting layer 220 b (Ag film) and the crystallizedfirst transparent electrode layer 210 (IZO film) have inferioradhesiveness.

On the other hand, the second transparent electrode layer 220 a, whichis amorphous (for example, an amorphous IZO film), and the reflectinglayer 220 b (Ag film) have excellent adhesiveness (bondingcharacteristics). Further, first transparent electrode layer 210 and thesecond transparent electrode layer 220 a, which is amorphous(non-crystalline), have excellent adhesiveness (bonding characteristics)and excellent conductivity. Accordingly, in the exemplary embodiment,the crystalline IZO film is formed as the first transparent electrodelayer 210 on the p-type semiconductor layer 160, and further, theamorphous IZO film is laminated as the second transparent electrodelayer 220 a, then the reflecting layer 220 b made of the Ag film isprovided thereon.

FIG. 8 is a diagram showing bonding characteristics between the p-typeGaN layer (p-type semiconductor layer 160) and the IZO film (or the Ptfilm).

Here, in the semiconductor light-emitting element 10 that is producedwithout providing the second transparent electrode layer 220 a, forwardcurrent If—forward voltage Vf characteristics were evaluated. Table 1indicates parameters regarding Cases 1 to 5 shown in FIG. 8. Case 1shows the characteristics in the case where IZO of the first transparentelectrode layer 210 is replaced with Pt. Cases 2 to 5 indicate thedifference in the state depending on the thickness and presence orabsence of the heat treatment providing that the first transparentelectrode layer 210 is the IZO film.

TABLE 1 Material Thickness (nm) State Case 1 Pt 5 Case 2 IZO 2 AmorphousCase 3 IZO 5 Amorphous Case 4 IZO 5 Crystalline (Heat treatment) Case 5IZO 10 Crystalline (Heat treatment)

As shown in FIG. 8, in the case of using the Pt film of Case 1, theforward voltage Vf in the case where the forward current If is constantbecomes high compared to Cases 2 to 5 where the IZO film is used. Inother words, the forward voltage Vf of the IZO film is lower than thatof the Pt film, and therefore the IZO film is excellent in the bondingcharacteristics with the p-type semiconductor layer 160.

Cases 2 and 3 show the case of the amorphous IZO film. In Case 2, thethickness of the IZO film is 2 nm, and in Case 3, the thickness of theIZO film is 5 nm. In Case 3, the forward voltage Vf is lower. It can beunderstood that the thicker (5 nm) IZO film is preferred.

Cases 4 and 5 show the case of the IZO film that has been subjected toheat treatment. In Case 4, the thickness of the IZO film is 5 nm, and inCase 5, the thickness of the IZO film is 10 nm. In FIG. 8, littledifference can be shown between them and they are overlapping. In otherwords, since the forward voltage Vf is substantially the same in Cases 4and 5, it can be understood that the thickness of the IZO film may be 5nm or more.

Cases 3 and 4 show the case where the thickness of the IZO film is 5 nm;Case 3 indicates the case of amorphous film, whereas Case 4 indicatesthe case of heat treatment (crystalline). When these are compared, inthe case of the crystalline IZO film, the forward voltage Vf is lowcompared to the case of amorphous film.

From above, it is preferable to form the crystalline IZO film having athickness of 5 nm or more on the p-type semiconductor layer 160, whichis p-type GaN.

EXAMPLES

Next, examples of the present invention will be described, but thepresent invention is not limited to the examples.

Examples 1 to 5

The semiconductor light-emitting element 10 used in Examples 1 to 5 hasthe same configuration as that shown in FIG. 2. The first electrode 200has the same configuration as that shown in FIG. 5. The second electrode300 has the same configuration as that shown in FIG. 6.

The substrate 110 is a sapphire substrate which is C-axis oriented. InExamples 1 to 5, the first transparent electrode layer 210 is the IZOfilm or the ITO film subjected to heat treatment. The thickness thereofdiffers in the examples 1 to 5. The second transparent electrode layer220 a is the amorphous IZO film with a thickness of 2 nm. The reflectinglayer 220 b is made of Ag, the first barrier layer 220 c is made of Ta,the first bonding layer 230 a is made of TaN, the second barrier layer230 b is made of Ta, the first metal layer 230 c is made of Pt, thesecond metal layer 230 d is made of Au and the second bonding layer 230e is made of Ta.

Comparative Example

On the other hand, Comparative example is configured similar to Example4 except that the second transparent electrode layer 220 a (amorphousIZO film) in Example 4 is not formed.

Table 2 indicates the evaluation results regarding Examples 1 to 5 andComparative example. The evaluation items are: the forward voltage Vffor the forward current If of 20 mA; the light emission wavelength λ;the light emission output Po; and the result of delamination test of thereflecting layer. It should be noted that the light emission wavelengthλ is a wavelength at a peak of the light emission intensity (peakwavelength).

The delamination test of the reflecting layer 220 b from the firsttransparent electrode layer 210 was performed based on a known tapedelamination test (tape test) upon depositing: the first transparentelectrode layer 210 described in Table 2 (material and thickness) on ap-type GaN layer (p-type semiconductor layer 160) prepared separatelyfrom the formation of the light-emitting element shown in FIG. 2; thesecond transparent electrode layer 220 a (except for Comparativeexample) on the first transparent electrode layer 210, the thicknessthereof being the same; and the reflecting layer 220 b on the secondtransparent electrode layer 220 a, the thickness thereof being the same.In the delamination test, 10 pieces of same test electrodes wereprepared, and the case where one or more pieces are delaminated wasrepresented as “X”, whereas the case where no delamination occurs wasrepresented as “O”.

TABLE 2 Bump formation Evaluation First transparent Submount side/ LightLight Delamination electrode layer Semiconductor Forward emissionemission test of Thickness light-emitting voltage wavelength output Poreflecting Material (nm) element side Vf (V) λ (nm) (mW) layer Example 1IZO 5 Submount side 3.2 452 20.7 ◯ Example 2 IZO 10 Submount side 3.2451 20.4 ◯ Example 3 ITO 20 Submount side 3.2 452 21.4 ◯ Example 4 IZO50 Submount side 3.2 451 22.9 ◯ Example 5 IZO 300 Submount side 3.2 45020.8 ◯ Example 6 IZO 50 Semiconductor 3.2 451 23.0 ◯ light-emittingelement side Comparative IZO 50 Submount side 3.2 451 22.8 X example

As shown in Examples 1, 2, 4 and 5, in the range of thickness of the IZOfilm of the first transparent electrode layer 210 from 5 nm to 300 nm,the light emission output Po indicates 22.9 mW at the maximum for thethickness of the IZO film of 50 nm, and is slightly decreased in thecase where the thickness of the IZO film is smaller or larger than thisvalue. However, the difference among these values is small.

On the other hand, as shown in Comparative example in Table 2, in thecase where the second transparent electrode layer 220 a is not formed onthe first transparent electrode layer 210, delamination easily occurredin the delamination test.

It should be noted that, in the Examples 1 to 5 and the Comparativeexample, the light emission wavelength λ is 450 nm to 452 nm, wherethere exists little difference. This is thought to be due to the sameconfiguration of the laminated semiconductor layer 100.

From above, by forming the first transparent electrode layer 210 withthe crystalline IZO (or ITO) and forming the second transparentelectrode layer 220 a with the amorphous IZO, the semiconductorlight-emitting element 10, in which the forward voltage Vf is low, thelight emission output is large, and no electrode delamination occurs,can be obtained.

FIG. 9 is a schematic diagram showing a result of observation through atransmission electron microscope (TEM) of a cross section of crystallineIZO film (first transparent electrode layer 210) and amorphous IZO film(second transparent electrode layer 220 a) laminated on the laminatedsemiconductor layer 100.

Specifically, the crystalline IZO film having a thickness of 5 nm (firsttransparent electrode layer 210) is formed on the laminatedsemiconductor layer 100, the amorphous IZO film having a thickness of 2nm (second transparent electrode layer 220 a) is further laminatedthereon, and still further, the reflecting layer 220 b made of an Aualloy is provided thereon. In the TEM image, the two-layer structure ofthe crystalline IZO film and the amorphous IZO film was able to bedistinctively observed.

In the exemplary embodiment, the first transparent electrode layer 210,which is crystalline, and the second transparent electrode layer 220 a,which is amorphous (non-crystalline), are used. Here, suppose that“crystalline” includes the case where the forward voltage Vf is reducedby applying heat treatment in addition to the state ofcrystallographically single crystal or polycrystal such as a case wherea peak is observed in the X ray diffraction or electron diffraction. Onthe other hand, “non-crystalline” includes the case where externalheating in film formation or temperature rise in film formation issuppressed, or the case where energy of particles involved in filmformation is kept low in addition to the state of crystallographicallyamorphous (non-crystalline) such as a case where a halo is observed inthe X ray diffraction or electron diffraction.

It should be noted that, in the exemplary embodiment, the semiconductorlight-emitting element 10, whose light emission peak wavelength λd isclose to 450 nm, is described, but the subject to which the presentinvention is applied is not limited thereto.

For example, it is obvious that the present invention can be applied toa semiconductor light-emitting element 10 that emits light of infraredto red, whose light-emitting layer is made of a compound semiconductor,such as Ga_(1-x)Al_(x)As (0<x<1), GaAs_(1-x)P_(x) (0<x<1) orIn_(1-x)Ga_(x)P (0<x<1), or a semiconductor light-emitting element 10that emits light of orange to green, in which AlP, AlAs, GaP or the likeis used for the light-emitting layer.

Further, as a subject to which the semiconductor light-emitting device 1according to the present invention can be applied, for example, anelectronic apparatus such as a liquid crystal display or an LED display,and further, an illumination device can be provided.

REFERENCE SIGNS LIST

-   1 . . . Semiconductor light-emitting device-   10 . . . Semiconductor light-emitting element-   15 . . . Submount-   20 . . . Submount substrate-   21, 24 . . . Submount wiring-   31, 34 . . . Bump-   100 . . . Laminated semiconductor layer-   110 . . . Substrate-   120 . . . Intermediate layer-   130 . . . Base layer-   140 . . . N-type semiconductor layer-   150 . . . Light-emitting layer-   160 . . . P-type semiconductor layer-   180 . . . Protecting layer-   200 . . . First electrode-   210 . . . First transparent electrode layer-   220 . . . Reflecting section-   220 a . . . Second transparent electrode layer-   220 b . . . Reflecting layer-   220 c . . . First barrier layer-   230 . . . Overcoat section-   230 a . . . First bonding layer-   230 b . . . Second barrier layer-   230 c . . . First metal layer-   230 d . . . Second metal layer-   230 e . . . Second bonding layer-   300 . . . Second electrode

1. A semiconductor light-emitting element comprising: a laminatedsemiconductor layer in which a first semiconductor layer having a firstconduction type, a light-emitting layer and a second semiconductor layerhaving a second conduction type that is opposite to the first conductiontype are laminated in order; a first transparent electrode layer that isprovided on the laminated semiconductor layer, has transparency to lightemitted from the light-emitting layer and is crystalline; a secondtransparent electrode layer that is provided on the first transparentelectrode layer, has transparency to the light and is non-crystalline;and a reflecting layer that is provided on the second transparentelectrode layer and is reflective to the light.
 2. The semiconductorlight-emitting element according to claim 1, wherein the firsttransparent electrode layer which is crystalline and the secondtransparent electrode layer which is non-crystalline are conductiveoxides.
 3. The semiconductor light-emitting element according to claim1, wherein the first transparent electrode layer which is crystallineand the second transparent electrode layer which is non-crystalline areconductive oxides containing any one of indium (In) and titanium (Ti).4. The semiconductor light-emitting element according to claim 1,wherein a thickness of the first transparent electrode layer which iscrystalline is in a range of 5 nm or more to 500 nm or less.
 5. Thesemiconductor light-emitting element according to claim 1, wherein athickness of the second transparent electrode layer which isnon-crystalline is in a range of 1 nm or more to 5 nm or less.
 6. Thesemiconductor light-emitting element according to claim 1, wherein thereflecting layer is any one of Ag and a metal containing Ag.
 7. Thesemiconductor light-emitting element according to claim 1, wherein, inthe laminated semiconductor layer, the first conduction type of thefirst semiconductor layer is an n-type in which a carrier is an electronand the second conduction type of the second semiconductor layer is ap-type in which a carrier is a hole.
 8. A semiconductor light-emittingdevice comprising: a semiconductor light-emitting element that includes:a laminated semiconductor layer in which a first semiconductor layerhaving a first conduction type, a light-emitting layer and a secondsemiconductor layer having a second conduction type that is opposite tothe first conduction type are laminated in order; a first transparentelectrode layer that is provided on the laminated semiconductor layer,has transparency to light emitted from the light-emitting layer and iscrystalline; a second transparent electrode layer that is provided onthe first transparent electrode layer, has transparency to the light andis non-crystalline; and a reflecting layer that is provided on thesecond transparent electrode layer and is reflective to the light; and acircuit board that is arranged to face a side including the reflectinglayer of the semiconductor light-emitting element.
 9. The semiconductorlight-emitting device according to claim 8, wherein, in thesemiconductor light-emitting element and the circuit board, a pair ofpositive and negative connecting electrodes provided on the sideincluding the reflecting layer of the semiconductor light-emittingelement is connected to a pair of wirings provided on the circuit boardby a connector provided on the circuit board.
 10. A method for producinga semiconductor light-emitting element, comprising: a process that formsa laminated semiconductor layer including a first semiconductor layerhaving a first conduction type, a light-emitting layer and a secondsemiconductor layer having a second conduction type that is opposite tothe first conduction type; a process that forms a first transparentelectrode layer on the laminated semiconductor layer, the firsttransparent electrode layer having transparency to light emitted fromthe light-emitting layer, and being crystalline; a process that forms asecond transparent electrode layer on the first transparent electrodelayer, the second transparent electrode layer having transparency to thelight, and being non-crystalline; and a process that forms a reflectinglayer on the second transparent electrode layer, the reflecting layerreflecting the light.
 11. The method for producing a semiconductorlight-emitting element according to claim 10, wherein the process thatforms a first transparent electrode layer includes a process thatdeposits a film to be the first transparent electrode layer and aprocess that applies heat treatment for crystallizing the film.
 12. Amethod for producing a semiconductor light-emitting device, comprising:a process that performs alignment to bring a pair of positive andnegative connecting electrodes provided on a side including a reflectinglayer of a semiconductor light-emitting element into correspondence witha pair of wirings provided on a circuit board, the semiconductorlight-emitting element including: a laminated semiconductor layer inwhich a first semiconductor layer having a first conduction type, alight-emitting layer and a second semiconductor layer having a secondconduction type that is opposite to the first conduction type arelaminated in order; a first transparent electrode layer that is providedon the laminated semiconductor layer, has transparency to light emittedfrom the light-emitting layer and is crystalline; a second transparentelectrode layer that is provided on the first transparent electrodelayer, has transparency to the light and is non-crystalline; and thereflecting layer that is provided on the second transparent electrodelayer and is reflective to the light; and a process that heats andpresses the semiconductor light-emitting element against the circuitboard.
 13. An illumination device comprising: a semiconductorlight-emitting device including: a semiconductor light-emitting elementthat includes: a laminated semiconductor layer in which a firstsemiconductor layer having a first conduction type, a light-emittinglayer and a second semiconductor layer having a second conduction typethat is opposite to the first conduction type are laminated in order; afirst transparent electrode layer that is provided on the laminatedsemiconductor layer, has transparency to light emitted from thelight-emitting layer and is crystalline; a second transparent electrodelayer that is provided on the first transparent electrode layer, hastransparency to the light and is non-crystalline; and a reflecting layerthat is provided on the second transparent electrode layer and isreflective to the light; and a circuit board that is arranged to face aside including the reflecting layer of the semiconductor light-emittingelement, the semiconductor light-emitting device being incorporated intothe illumination device.
 14. An electronic apparatus comprising: asemiconductor light-emitting device including: a semiconductorlight-emitting element that includes: a laminated semiconductor layer inwhich a first semiconductor layer having a first conduction type, alight-emitting layer and a second semiconductor layer having a secondconduction type that is opposite to the first conduction type arelaminated in order; a first transparent electrode layer that is providedon the laminated semiconductor layer, has transparency to light emittedfrom the light-emitting layer and is crystalline; a second transparentelectrode layer that is provided on the first transparent electrodelayer, has transparency to the light and is non-crystalline; and areflecting layer that is provided on the second transparent electrodelayer and is reflective to the light; and a circuit board that isarranged to face a side including the reflecting layer of thesemiconductor light-emitting element, the semiconductor light-emittingdevice being incorporated into the electronic apparatus.